Study Of Balance Of Water And Salt And Ecological Water Demand For Arid Irrigation District Based On Remote Sensing Technology

Hetao irrigation district is the biggest water user, along the Yellow River in Inner Mongolia region, accounting for about 85% of the quota of the Yellow River water in Inner Mongolia. However, the Yellow River water and water resources as a unified scheduling, the Yellow River water of Hetao irrigation district is restricted, it not only affects agricultural production of irrigation disreict seriously, but also hinders local economic development, strengthening salt dynamic observation of groundwater for irrigation district and study of ecological water requirement have great significance for the guidance of current management and ecological construction for irrigation district.In this paper, based on the analysis of precipitation, surface water and groundwater, using the remote sensing technology (RS) on the ecosystem in Hetao Irrigation District classification, and inversion calculating evapotranspiration of Hetao Irrigation District; with the support of water and salt balance theory, and analysis of relevant water and salt data in Hetao Irrigation District, on the basis of quantitative analysis and a reasonable calculation of a displacement of irrigated areas. Through a combination of both, all kinds of irrigation water elements of the ecological water requirement are calculated, and at last the ecological water demand of the different ecosystems is determined.In this paper, the conclusions are as follows:(1) Through the analysis remote sensing data, the best band combination of the TM images is determined, after geometric correction and non-supervised classification of image classification, the land classification and crop planting structure of Irrigation District eventually zre determined. Using high-resolution IKONOS image to assessment the accuracy of results, the accuracy analysis prove that land-use classification of TM image has a high accuracy for the scale of irrigated district.(2) Using the high-frequency multi-temporal MODIS data to extract the crops structure can effectively overcome the impact of human factors, and it can extract crop acreage irrigated areas and its spatial distribution accuratly.(3) Using of the principle of surface energy balance model of SEBAL and SEBS model to derive and calculate evapotranspiration, inversion results with the measured value of error was allowed for the study area, it provides a new method of water consumption for Hetao Irrigation District. (4) Based on land classification of irrigation district, combined with the DEM data of CIAT-CSI SRTM website, through the sampling and analysis, the saline irrigation area Hetao irrigated areas are mainly distributed in the middle reaches of 1030m above the ground elevation of the irrigation channels and drains on both sides of road.(5) Through the analysis of salt of the irrigation district, we found that there was a significant difference between the salt content and composition of irrigation water and drainage. Accumulation of harmful cations in the irrigation distrct is about 0.3185 million ton per year. The salt, in the wasteland, does not accumulate in Irrigation District. The use of index for harmful salt can assessment the effect of irrigation water more reasonably. It provides a new method of reasonable assessment for the drainage water of Hetao irrigation district.(6) Using the principle of water and soil balance, to calculate the ecological water demand theoretically. The Hetao Irrigation District to maintain the status quo of ecological water requirements is about 5305.3 million m3. The total supply is larger than the water required for irrigation district, but the remaining water is 155.6 million m3, the volume is small, it has less potential for further water conservation.